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First Determined (first + determine)
Selected AbstractsPressure-independent cardiac effects of angiotensin II in pigsACTA PHYSIOLOGICA, Issue 2 2004M. Broomé Abstract Background:, Angiotensin II (Ang II) is a potent vasoconstrictor with an important role in the development of cardiovascular disease. Earlier results have shown a positive acute inotropic effect of Ang II in anaesthetized pigs together with significant vasoconstriction. This investigation was designed to study cardiac effects of Ang II, when blood pressure was maintained constant by experimental means. Methods:, Ang II (200 ,g h,1) was infused in anaesthetized pigs (n = 10) at two different arterial blood pressures, the first determined by the effects of Ang II alone, and the second maintained at baseline blood pressure with nitroprusside. Cardiac systolic and diastolic function was evaluated by analysis of left ventricular pressure,volume relationships. Results:, Heart rate, end-systolic elastance (Ees) and pre-load adjusted maximal power (PWRmax EDV,2) increased at both blood pressure levels, although less when blood pressure was kept constant with nitroprusside. The time constant for isovolumetric relaxation (,1/2) was prolonged with Ang II alone and shortened with Ang II infused together with nitroprusside. Conclusion:, Ang II infusion in the pig has inotropic and chronotropic properties independent of arterial blood pressure levels, although the effects seem to be blunted by pharmacological actions of the nitric oxide donor nitroprusside. [source] Transformation of 2,4,6-trinitrotoluene in soil in the presence of the earthworm Eisenia andrei,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Agnès Y. Renoux Abstract The ability of the earthworm Eisenia andrei to metabolize 2,4,6-trinitrotoluene (TNT) was studied in experiments with TNT-spiked soils, dermal contact tests, and with an in vitro assay. Lethality of TNT in a forest sandy soil was first determined (14-d LC50 = 143 mg/kg). Then TNT at lethal and sublethal concentrations was applied to the same soil and was monitored along with its metabolites in extracts of soil and earthworm tissue for up to 14 d postapplication. High performance liquid chromatography-ultra violet analyses indicated that TNT was transformed in the presence of E. andrei by a reductive pathway to 2-amino-4,6-dinitrotoluene (2-ADNT), 4-amino-2,6-dinitrotoluene (4-ADNT), 2,4-diamino-6-nitrotoluene (2,4-DANT), and traces of 2,6-di-amino-4-nitrotoluene (2,6-DANT) in earthworm tissues. This transformation could be explained by either a metabolic mechanism within the earthworm or by the enhancement of an earthworm-associated microbial activity or both. The TNT concentrations decreased from the spiked soils. However, the monoamino-dinitrotoluene (2-ADNT and 4-ADNT) concentrations increased with exposure duration and were dependent on the initial TNT soil concentrations. This was also observed to a lesser extent in the TNT-spiked soils with no earthworms present. The biotransformation of TNT into 2-ADNT, 4-ADNT, and 2,4-DANT and the presence of these metabolites in E. andrei after dermal contact on TNT-spiked filter paper showed that dermal uptake can be a significant exposure route for TNT. In vitro experiments showed that earthworm homogenate could metabolize TNT and form 2-ADNT and 4-ADNT at room temperature and at 37°C. This effect was inhibited by heat inactivation prior to incubation or by incubation at 4°C, suggesting that the biotransformation of TNT in the presence of E. andrei may be enzymatic in nature. [source] Identification of novel genes regulated by ,-melanocyte-stimulating hormone in murine bone marrow-derived dendritic cellsEXPERIMENTAL DERMATOLOGY, Issue 9 2004T. Brzoska Many strains of evidence indicate that ,-melanocyte-stimulating hormone (,-MSH) elicits its immunomodulatory activity via binding to melanocortin receptors (MC-Rs) expressed on monocytes and dendritic cells. In order to identify novel target genes regulated by ,-MSH in these cells, we prepared bone marrow-derived dendritic cell precursors from BALB/c mice and treated them with GM-CSF and IL-4 for 6 days. The MC-R profile on these immature dendritic cells was first determined by quantitative RT-PCR. Both transcripts for MC-1R and MC-5R were detected in these cells. Cells were subsequently stimulated with dinitrobenzene sulfonic acid (DNBS), ,-MSH or both substances for 2 or 16 h. After RNA preparation, cDNA synthesis and in vitro transcripton hybridization of biotinylated cRNA samples was performed on MG U74A Affymetrix gene chips. Data evaluation, cleansing, extraction and analysis of the more than 12 000 cloned genes and expressed sequence tags were performed using the GENE DATA ANALYST vs. 1 Expressionist software. Filter criteria included a minimum threshold of 100, normalization by the logarithmic mean and a quality setting of P < 0.04. Changes with a change factor of >2 were regarded as significant. As expected, stimulation with DNBS resulted in induction or upregulation of genes encoding proinflammatory cytokines, growth factors, signal transduction intermediates and transcription factors. Treatment with ,-MSH blocked the DNBS-driven upregulation of several known genes such as IL-1 or CD86. On the other hand, ,-MSH modulated the expression of several novel genes implicated in immunomodulation, e.g. IL-1, converting enzyme, IFN-, receptor, FK506-binding proteins or several neuropeptides and their receptors. These data indicate novel molecular targets by which ,-MSH exerts its immunomodulatory activities in immunocompetent cells. [source] Separation of fullerenes C60 and C70 using a crystallization-based processAICHE JOURNAL, Issue 7 2010Kui S. Kwok Abstract A crystallization-based process that separates pure fullerenes C60 and C70 from their mixture using o-xylene as the solvent has been developed. Isothermal solid,liquid equilibrium phase diagrams of the C60 -C70 -o-xylene ternary system for a number of temperatures were first determined at 1 atm. Taking advantage of the shift in solvent-free composition of the C60 -C70 double saturation point with temperature and based on the solid solution-forming phase behavior between C60 and C70, the flowsheet of a general crystallization process was then synthesized. It involved the fractionation of a C60 -C70 fullerene mixture into C60 -rich and C70 -rich solid solutions using temperature-swing crystallization, followed by purification of the solid solutions with multistage crystallization into pure C60 and C70 solids. To demonstrate process feasibility, bench-scale batch experiments were performed using a commercially available fullerene mixture that was pretreated by adsorption to remove higher fullerenes. C60 and C70 solids of purity higher than 99 wt % were obtained. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Concentration polarization in a narrow reverse osmosis membrane channelAICHE JOURNAL, Issue 1 2010Lianfa Song Abstract Concentration polarization in a narrow reverse osmosis channel is bounded by the channel height and under the influence of variable transverse velocity. An attempt was made in this article to quantify concentration polarization in such a narrow membrane channel. The transverse velocity in the membrane channel was first determined and its impact on concentration polarization was investigated. Based on the concept of retained salt, analytical equations were developed for the wall salt concentration at an arbitrary point in the narrow membrane channel. Finally, development of concentration polarization in typical reverse osmosis channels under various conditions was numerically simulated and discussed. Interesting results on the details of concentration polarization in the narrow reverse osmosis channel that had never been reported before were revealed with this mechanistic model. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Solid-state glycation of ,-lactoglobulin by lactose and galactose: localization of the modified amino acids using mass spectrometric techniquesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2004François Fenaille Abstract The Maillard reaction is commonly encountered during food processing or storage, and also in human nutrition, hence there is a need for analytical methodologies to identify and characterize the modified proteins. This paper reports specific methods using mass spectrometric techniques to localize protein modifications induced by lactose and galactose on ,-lactoglobulin (,-Lg) under solid-state glycation conditions. The extent of glycation was first determined by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). The specific identification of lactose-modified amino acid residues was realized using both NanoESI-MS, NanoESI-MS/MS (neutral loss scanning modes) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) (with and without guanidination of lysine residues) on unfractionated digests. The results indicated that, after 8.25 h of incubation, the lysine residues were the main targets of lactose-induced modification. In addition to the 15 lysine residues, Leu1 (NH2 terminal) and the Arg124 were also found to be modified, thus leading to a total of 17 different modified amino acid residues (versus 15 found by LC/ESI-MS measurement). In a second set of experiments, different strategies consisting of constant neutral loss and precursor ion scanning were compared to characterize galactose-induced modifications. Owing to the high level of ,-Lg glycation, the combined use of these different strategies appeared to be necessary for determining the galactose-modified sites after 8.25 h of incubation. Thus, among the 22 galactose adducts deduced from the LC/ESI-MS measurement, apart from the N-terminal and classical lysine residues, we also observed a few arginine residues (Arg40, Arg124 and Arg148) that were modified, and also dialkylations on specific lysine residues (Lys47, Lys75). Copyright © 2003 John Wiley & Sons, Ltd. [source] On the structure of aragonite , Lawrence Bragg revisitedACTA CRYSTALLOGRAPHICA SECTION B, Issue 3-2 2002Elisabeth Rossmanith The structure of aragonite was first determined by Lawrence Bragg in 1924 in what is the now standard space-group setting Pnma (No. 62). Subsequent studies have all taken his structure as their starting points, despite Bragg's own stated doubts and some earlier etching studies which indicated that the underlying symmetry may really be polar. We have reinvestigated the structure and found that there are many reflections with significant intensity among those that should be systematically extinct in Pnma. Some of these reflections have been subjected to further experimental analysis and have been shown not to be due to Renninger effects. A possible model that satisfies these observations is one where the true structure is in space group P and the structure is twinned about the three axial twofold rotation axes of Pnma. The space group P1 cannot be ruled out. Evidence for these conclusions is presented. The crystal chemistry of aragonite is revisited and described in terms of the stuffed alloy CaC. The carbonate group is confirmed to be non-planar in the crystal. [source] Error propagation from prime variables into specific rates and metabolic fluxes for mammalian cells in perfusion cultureBIOTECHNOLOGY PROGRESS, Issue 4 2009Chetan T. Goudar Abstract Error propagation from prime variables into specific rates and metabolic fluxes was quantified for high-concentration CHO cell perfusion cultivation. Prime variable errors were first determined from repeated measurements and ranged from 4.8 to 12.2%. Errors in nutrient uptake and metabolite/product formation rates for 5,15% error in prime variables ranged from 8,22%. The specific growth rate, however, was characterized by higher uncertainty as 15% errors in the bioreactor and harvest cell concentration resulted in 37.8% error. Metabolic fluxes were estimated for 12 experimental conditions, each of 10 day duration, during 120-day perfusion cultivation and were used to determine error propagation from specific rates into metabolic fluxes. Errors of the greater metabolic fluxes (those related to glycolysis, lactate production, TCA cycle and oxidative phosphorylation) were similar in magnitude to those of the related greater specific rates (glucose, lactate, oxygen and CO2 rates) and were insensitive to errors of the lesser specific rates (amino acid catabolism and biosynthesis rates). Errors of the lesser metabolic fluxes (those related to amino acid metabolism), however, were extremely sensitive to errors of the greater specific rates to the extent that they were no longer representative of cellular metabolism and were much less affected by errors in the lesser specific rates. We show that the relationship between specific rate and metabolic flux error could be accurately described by normalized sensitivity coefficients, which were readily calculated once metabolic fluxes were estimated. Their ease of calculation, along with their ability to accurately describe the specific rate-metabolic flux error relationship, makes them a necessary component of metabolic flux analysis. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Anatomical development of urinary bladder during the fetal periodCLINICAL ANATOMY, Issue 7 2008O. Sulak Abstract The aim of this study was to determine the development, location, and size of the urinary bladder during the fetal period. The study was performed on 149 human fetuses between 9 and 40 weeks of gestation. The location of the urinary bladder with respect to transverse plane between the highest point of pubic symphysis and the sacral promontory and median sagittal plane was first determined. The dimensions and the angle of the urinary bladder were measured, and bladder shapes were determined. In addition, the edges of the vesical trigone were measured. There was no significant difference between sexes for any of the parameters (P > 0.05). A significant correlation was observed between all parameters and gestational age (P < 0.001). The urinary bladder was located above the transverse plane in most of the cases (83%) and in the median sagittal plane in every case. It was determined that the angle of bladder did not change and the mean value of the angle was 151° during the fetal period. Bladder was categorized into four different shapes (ellipsoid, round, cuboid, and triangular), and the most common shape found during the fetal period was cuboid. The vesical trigone was an isosceles triangle during the fetal period. The new data provided by this study will enable evaluation of the development of the fetal urinary bladder, and should be useful in several fields such as anatomy, fetopathology, medical imaging, obstetrics, and pediatric urology. Clin. Anat. 21:683,690, 2008. © 2008 Wiley-Liss, Inc. [source] The International Caries Detection and Assessment System (ICDAS): an integrated system for measuring dental cariesCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 3 2007A. I. Ismail Abstract,,, This paper describes early findings of evaluations of the International Caries Detection and Assessment System (ICDAS) conducted by the Detroit Center for Research on Oral Health Disparities (DCR-OHD). The lack of consistency among the contemporary criteria systems limits the comparability of outcomes measured in epidemiological and clinical studies. The ICDAS criteria were developed by an international team of caries researchers to integrate several new criteria systems into one standard system for caries detection and assessment. Using ICDAS in the DCR-OHD cohort study, dental examiners first determined whether a clean and dry tooth surface is sound, sealed, restored, crowned, or missing. Afterwards, the examiners classified the carious status of each tooth surface using a seven-point ordinal scale ranging from sound to extensive cavitation. Histological examination of extracted teeth found increased likelihood of carious demineralization in dentin as the ICDAS codes increased in severity. The criteria were also found to have discriminatory validity in analyses of social, behavioral and dietary factors associated with dental caries. The reliability of six examiners to classify tooth surfaces by their ICDAS carious status ranged between good to excellent (kappa coefficients ranged between 0.59 and 0.82). While further work is still needed to define caries activity, validate the criteria and their reliability in assessing dental caries on smooth surfaces, and develop a classification system for assessing preventive and restorative treatment needs, this early evaluation of the ICDAS platform has found that the system is practical; has content validity, correlational validity with histological examination of pits and fissures in extracted teeth; and discriminatory validity. [source] | ||||||||||||||||